Method of bearer deletion, device, and system

ABSTRACT

A method of bearer deletion is provided to improve the universality of the bearer deletion process. The method includes: receiving, by the original intermediate NE, the cancellation type indication parameter sent by the HSS, and deleting the bearer between the serving gateway (S-GW) and a packet data network gateway (P-GW), if the original intermediate network element obtains an attach type according to the cancellation type indication parameter indicating an attach type and a corresponding bearer exists on the original intermediate NE. This method helps efficiently improve the universality of the bearer deletion flow.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/281,112, filed on Sep. 30, 2016, which is a continuation of U.S.patent application Ser. No. 13/949,650, filed on Jul. 24, 2013, now U.S.Pat. No. 9,747,038. U.S. patent application Ser. No. 13/949,650 is acontinuation of U.S. patent application Ser. No. 12/691,068, filed onJan. 21, 2010, now U.S. Pat. No. 8,520,593. U.S. patent application Ser.No. 12/691,068 is a continuation of International Application No.PCT/CN2008/071755, filed on Jul. 25, 2008. The International Applicationclaims the priority to Chinese patent application No. 200710130053.5,filed on Jul. 25, 2007. All of the afore-mentioned patent applicationsare hereby incorporated by reference in their entireties.

TECHNICAL FIELD

The present disclosure relates to the telecommunication field, and inparticular, to a method of bearer deletion, home location register (HLR)and relevant device.

BACKGROUND

With the development of network technologies, new types of networkstructures emerge, such as the System Architecture Evolved (SAE). Duringthe promotion of the SAE, the scenario in which an area is covered byboth the SAE network and an existing network, such as a 2G or 3Gnetwork, occurs. As shown in FIG. 1, routing area (RA) 1 and RA 2 arecovered by an existing 2G/3G network. A user equipment (UE) in the 2G/3Gnetwork needs to initiate a routing area update (RAU) request every timeto change the RA. Tracking area (TA) 1 and TA 2 are tracking areas ofthe SAE network, similar to RAs in the 2G/3G network. TA 1 hasintersected coverage with RA 1. In this case, when a multi-mode UE movesbetween these areas, the UE may frequently initiate network registrationrequests. For example, when the UE enters into RA 1, the UE registerswith a serving GPRS support node (SGSN) of the 2G/3G network. When theUE enters into TA 1, the UE registers with a mobility management entity(MME) of the SAE network. When the UE moves from TA 1 to RA 1, the UEneeds to register with the SGSN of the 2G/3G network again. Thus,significant air interface resources are wasted.

The bearer deletion method in the existing technologies applies to asingle network. For example, after a UE performs the attach procedure ina 2G/3G network, if the SGSN is changed, the original attached SGSNreceives the Cancel Location request from a home location register (HLR)and sends a Delete PDP Context Request message to a gateway GPRS supportnode (GGSN) to request for deleting the PDP context information when theUE exits upon exception last time. If no SGSN change occurs, the SGSNsends a Delete PDP Context Request message to the GGSN to request fordeleting the PDP context information when the UE exits upon exceptionlast time. That is, when the UE initiates an attach request or entersinto a certain radio access technology (RAT) network by using the radioaccess technology for the first time and initiates an update locationrequest, the accessed SGSN or MME needs to initiate a request to theserving gateway (S-GW) and PDN gateway (P-GW) to delete the originalbearer if any. If no original bearer exists, the SGSN or MME initiatesan update location request to the HSS. The HSS sends a cancel locationrequest to the original SGSN or MME. If the original SGSN or MME has anoriginal bearer, the SGSN or MME needs to initiate a request to theserving gateway (S-GW) and PDN gateway (P-GW) to delete the originalbearer.

SUMMARY

Bearer deletion schemes as described above are not applicable acrossnetworks. To prevent duplicative UE registrations, the idle modesignaling reduction (ISR) rule is introduced to the existing technology.The core idea is as follows: A UE registers with a type of accessnetwork after the attach procedure. Then, the UE moves to another typeof access network and registers with the access network. In this case,the UE can be registered with two types of access networks. When the UEmoves between these two types of access networks, the UE does notinitiate registration requests any more, thus conserving networkresources.

A method of bearer deletion, a device, and a system are provided hereinto improve the universality of the bearer deletion process.

A method of bearer deletion, a serving gateway, and a user device areprovided herein to distinguish between the afore-mentioned scenarios andperform related processing to avoid problems due to incorrect deletionof the S-GW/P-GW bearer.

The bearer deletion method includes:

receiving, by an original intermediate network element (NE), acancellation type indication parameter sent by a home subscriber server(HSS), and deleting a bearer between the original intermediate NE andthe serving gateway (S-GW) and a bearer between the S-GW and the PDNgateway (P-GW) if the original intermediate Network Element obtains anattach type according to the cancellation type indication parameterindicative of an attach type and the existence of a bearer on theoriginal intermediate NE.

An intermediate network element (NE) is provided in an embodiment of thepresent disclosure. The intermediate NE includes:

a receiving unit, configured to receive a Cancel Location message thatcontains the cancellation type indication parameter from the HSS; and

a deletion unit, configured to delete a bearer between the intermediateNE and the S-GW and the bearer between the S-GW and the P-GW when thecancellation type indication parameter indicates an attach type and acorresponding bearers exists.

A further embodiment of an intermediate NE includes:

a receiving unit, configured to receive a context acknowledgementmessage or an explicit signaling sent by a new intermediate NE, andcancellation type indication parameter from a Home Subscriber Server(HSS); and

a deletion unit, configured to delete a bearer between the intermediateNE and an S-GW if the context acknowledgement message or the explicitsignaling contains an S-GW Change flag and a corresponding bearer existson the intermediate NE.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an overlapped coverage of the networks that use theexisting technologies;

FIG. 2 shows a first case of the bearer deletion method according to anembodiment of the present disclosure;

FIG. 3 shows a second case of the bearer deletion method according to anembodiment of the present disclosure;

FIG. 4 shows a third case of the bearer deletion method according to anembodiment of the present disclosure;

FIG. 5 shows a fourth case of the bearer deletion method according to anembodiment of the present disclosure;

FIG. 6 shows a fifth case of the bearer deletion method according to anembodiment of the present disclosure;

FIG. 7 shows a sixth case of the bearer deletion method according to anembodiment of the present disclosure;

FIG. 8 shows a first case of the intermediate NE according to anembodiment of the present disclosure;

FIG. 9 shows a second case of the intermediate NE according to anembodiment of the present disclosure;

FIG. 10 shows an HSS according to an embodiment of the presentdisclosure; and

FIG. 11 shows an S-GW according to an embodiment of the presentdisclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

After ISR is activated, the following scenario may occur: If a UE withactivated ISR moves from an SGSN to a new MME, the UE establishes aconnection with the original S-GW, and maintains the ISR status. The newMME obtains the context information from the SGSN and the SGSN does notperform any action. The original MME receives the Cancel Locationrequest from the HSS and deletes the UE context information from itself.Difficulty arises in distinguishing between the two actions of (a)receiving the Cancel Location request, that is, the action of initiatinga procedure for deleting the bearers with the S-GW and P-GW when bearersexist, and (b) the action of deleting its own bearer. The SGSN connectsto the S-GW. The S-GW connects to the P-GW. The bearer deletion schemessupported by the existing technologies are used to delete bearers insidea single network, but are not applicable across networks. As a result,the universality of the bearer deletion procedure is affected.

A method of bearer deletion, a device, and a system are provided hereinto improve the universality of the bearer deletion process.

The method of bearer deletion provided herein is divided into two types:

-   -   Type I. Cancel Location procedure triggered inside the system    -   Type II. Cancel Location procedure triggered in two networks

Type I cancel location procedures can be further divided into thefollowing five cases:

Case One: The UE registers with the Universal Mobile TelecommunicationSystem (UMTS).

FIG. 2 shows the first case of the bearer deletion method in anembodiment of the present disclosure, including:

Step 201: The UE sends an attach request.

The UE initiates an attach request to the new SGSN.

Step 202: The new SGSN interacts with the original SGSN to identify theUE.

If the new SGSN is not the SGSN originally registered by the UE, the newSGSN sends an identification request to the original SGSN to obtain theInternational Mobile Subscriber Identity (IMSI) of the UE.

Step 203: The new SGSN initiates an identification request to the UE toobtain the IMSI of the UE.

Step 204: The authentication procedure may be performed.

The UE performs authentication with the HSS through the new SGSN.

Step 205: The new SGSN initiates a PDP context deletion request or abearer deletion request if the new SGSN is the SGSN originallyregistered by the UE and a bearer that is left due to last abnormalpower-off of the UE exists. That is, the new SGSN sends a Delete PDPContext Request or a Delete Bearer Request message to the S-GW.

Step 206: The S-GW sends a bearer deletion request.

The S-GW sends a bearer deletion request to the P-GW.

Step 207: The P-GW sends a bearer deletion response to the S-GW.

Step 208: The S-GW sends a PDP context deletion response or a bearerdeletion response to the new SGSN.

Step 209: If the new SGSN is not the SGSN originally registered by theUE, the new SGSN sends an Update Location request to the HSS.

Step 210: The original SGSN sends a Cancel Location request to the HSS.

Step 211: If the new SGSN is not the SGSN originally registered by theUE and a bearer that is left due to last abnormal power-off of the UEexists, the PDP context between the original SGSN and the S-GW isdeleted.

Step 212: A request for deleting the bearer between the S-GW and theP-GW is sent.

Step 213: The HSS may insert the data about the UE to the new SGSN.

Step 214: The HSS sends an Update Location response to the new SGSN.

Step 215: The new SGSN sends a message that indicates attach accepted tothe UE. The attach procedure is complete.

In the first case of the bearer deletion method, steps 205 to 208, step211, and step 212 are the procedures for deleting an original bearer. Ifthe SGSN that the UE last detached is the SGSN that the UE attaches thistime, and original PDP Context information exists, steps 205 to 208 areperformed and steps 209 to 214 are skipped.

If the SGSN that the UE last detached is not the SGSN that the UEattaches this time, and the original SGSN contains the original PDPContext information, steps 211 and 212 are performed and steps 205 to208 are skipped.

After receiving the Delete PDP Context Request message, the S-GWtriggers the procedure for deleting the bearer between the S-GW and theP-GW.

Case Two: The UE registers with the UMTS and then moves to the SAE.

FIG. 3 shows the second case of the bearer deletion method in anembodiment of the present disclosure, including:

Step 301: The UE sends an Area Update request.

The UE sends a TAU Request message to the new MME.

Step 302: The new MME sends a context request to the originallyregistered SGSN, that is, original SGSN.

Step 303: The original SGSN sends a context response to the new MME.

Step 304: The authentication procedure may be performed.

Step 305: If the new MME is the MME that the UE last detached or abearer that is left due to last abnormal power-off of the UE exists, thenew MME sends a bearer deletion request.

The new MME sends a bearer deletion request to the S-GW.

Step 306: The S-GW sends a bearer deletion request to the P-GW.

Step 307: The P-GW sends a bearer deletion response to the S-GW.

Step 308: The S-GW sends the bearer deletion response to the new MME.

Step 309: The new MME sends the Context acknowledgement message orexplicit signaling to the SGSN.

Step 310: The new MME sends a request for creating a bearer to the S-GWto ensure that the bearers in the 2G and 3G networks are consistent.

Step 311: The S-GW sends a bearer update request to the P-GW.

Step 312: The P-GW sends a bearer update response to the S-GW.

Step 313: The S-GW sends the bearer setup response to the new MME.

Step 314: If the new MME is not the MME that the UE last detached, thenew MME sends an Update Location request to the HSS.

Step 315: The original MME and the HSS perform the Cancel Locationprocedure.

Step 316: If the original MME finds a bearer that is left due toabnormal power-off of the UE, the original MME deletes the bearer.

Step 317: The bearer between the S-GW and the P-GW is deleted.

Step 318: The HSS may insert the data about the UE to the new MME.

Step 319: The HSS sends an Update Location response to the new MME.

Step 320: The new MME sends a message to the UE, indicating that the TAUrequest is accepted.

Step 321: If the Serving Temporary Mobile Station Identity (S-TMSI) ischanged, the UE sends a message to the new MME, indicating that the TAUis complete.

In the second case of the bearer deletion method, when the ISR rule isactivated, the UE initiates the TAU but not Attach procedure afterentering into the SAE network. The new MME obtains the UE contextinformation from the SGSN. If the new MME is the MME that the UE lastdetached, the new MME needs to delete the bearer that is left due tolast abnormal power-off of the UE after obtaining the IMSI of the UE.Therefore, steps 205 to 208 are performed. The new MME sends a DeleteBearer Request message to the Tunnel Endpoint ID (IEID) of the GPRSTunneling Protocol for Control Plane (GTP-C) allocated by the S-GW,requesting the S-GW to delete the bearer. The S-GW sends a bearerdeletion request to the P-GW.

If the MME is changed, the Update Location procedure in the HSS istriggered. The HSS sends a Cancel Location request to the original MME.The UE enters into the SAE network for the first time. Therefore, toavoid any bearer that is left due to last abnormal power-off of the UEin the original MME, the original MME sends a request for deletingbearers between the MME and the S-GW and between the S-GW and the P-GW.

In the preceding procedure, the new MME receives the TAU request andobtains the context information from the SGSN. However, the new MMEneeds to delete the original context information because the UEregisters with the SAE network for the first time. Normally, afterreceiving the TAU request, the new MME does not delete the contextinformation. The possible causes for triggering the context deletionprocedure are as follows:

A. The TAU request sent by the UE contains the registration flag. Thisflag indicates that the UE registers with the SAE network for the firsttime. The registration flag, such as attach flag, means that the UEattaches the SAE network.

B. The new MME obtains the context information from the SGSN and knowsthat a procedure similar to the Attach procedure is performed. If theSGSN has not established an ISR association with the MME, a flag can becarried. If the SGSN has established association with the original MME,the flag or other parameters are carried. If no such association isestablished, the flag or parameters are not carried. In this case, thenew MME learns that the procedure is similar to the UE Attach procedureand the original bearer needs to be deleted.

The preceding is the processing flow for a UE that registers with a UMTSnetwork and then moves to an SAE network. The processing flow for a UEthat registers with an SAE network and then moves to a UMTS network issimilar to the preceding flow.

The scenario in which the network entity is changed is described asfollows:

Case Three: The UE switches from an SGSN to an MME when ISR isactivated.

FIG. 4 shows the third case of the bearer deletion method in anembodiment of the present disclosure, including:

Step 401: The UE sends a TAU request.

The UE sends a TAU Request message to the new MME.

Step 402: The new MME sends a context request to the SGSN.

Step 403: The original SGSN sends the context information to the newMME.

Step 404: The authentication procedure may be performed.

Step 405: The new MME sends the Context acknowledgement message orexplicit signaling to the SGSN.

Step 406: A new bearer needs to be established because the MME ischanged.

The new MME sends a bearer setup request to the S-GW.

Step 407: If the S-GW is changed, a bearer update request is sent.

The S-GW sends a bearer update request to the P-GW.

Step 408: The P-GW sends a bearer update response.

Step 409: The S-GW sends a bearer setup response.

Step 410: The new MME sends an Update Location request to the HSS.

Step 411: The original MME and the HSS perform the Cancel Locationprocedure.

Step 412: If the S-GW is changed, the original MME sends a request fordeleting the bearer to the S-GW. If the S-GW is not changed, theoriginal MME deletes the UE context information stored in the originalMME.

Step 413: The HSS may insert the data about the UE to the new MME.

Step 414: The HSS sends an Update Location response to the new MME.

Step 415: The new MME sends a message to the UE, indicating that the TAUrequest is accepted.

Step 416: The UE sends a message to the new MME, indicating that the TAUis complete.

As shown in FIG. 3 and FIG. 4, the original MME receives the CancelLocation request from the HSS, and deletes the bearer with the P-GW ordeletes the bearer with the S-GW or the context information on the MMEdepending on whether the S-GW is changed. Therefore, in the currentmechanism, it is hard to differentiate bearer deletion operations.Several methods are provided herein to correctly differentiate bearerdeletion operations.

Four bearer deletion methods (Methods A-D below) are described herein,including but not limited to:

Method A: After a UE accesses a certain system, the UE obtains thecontext information from the original intermediate NEs in all thesystems accessed by the UE if ISR is activated.

For example, after the UE accesses a new MME, the new MME obtains the UEcontext information from the original MME and original SGSN. Theoriginal MME learns whether the UE accesses the new MME for the firsttime according to the Context acknowledgement message. In addition, theoriginal MME learns the S-GW change information. Based on the precedinginformation, the original MME determines whether to initiate a requestfor deleting the bearer with the S-GW. If the S-GW is changed, theoriginal MME deletes the bearer between the new MME and the originalS-GW. If the S-GW is not changed, the original MME deletes the UEcontext information stored in the original MME. If the UE accesses thesystem for the first time, the original MME deletes the bearer betweenthe new MME and the P-GW. If the UE accessed the system before, thebearer between the new MME and the P-GW does not need to be deleted. Or,if the UE accesses the system for the first time, the original MME doesnot initiate a context request to the new MME. Therefore, the originalMME determines how to delete the bearer based on whether it receives thecontext request/acknowledgement and whether the S-GW Change flag iscontained in the message. For example, in this instance, the originalMME decides not to initiate a request for deleting the bearer with theP-GW based on the received Context Request and Context acknowledgementmessages. However, if the S-GW is changed, the original MME initiates arequest for deleting the bearer with the S-GW; otherwise, the originalMME deletes the UE context information stored in the original MME.

That is, the new intermediate NE obtains the context information fromthe original intermediate NEs from the two systems and sends a Contextacknowledgement message to the original intermediate NE in the systemwhere the new intermediate NE is located. The message contains theUpdate/Attach flag and S-GW Change flag or similar information. Theoriginal intermediate NE in the same system decides how to delete thebearer based on this information. Attach means to delete the bearer tothe P-GW after receiving the Cancel Location message. Or, if the Attachflag is contained in the message, the new intermediate NE does notobtain the context information from its own system. If the Update flagis contained, the new intermediate NE obtains the context informationfrom the two systems. In this case, the original intermediate NE in thesystem where the new intermediate NE is located initiates a request fordeleting the bearer with the P-GW after receiving the Cancel Locationmessage from the HSS. Otherwise, if the Context Request or Contextacknowledgement message is received, the new intermediate NE decideswhether to delete the context information or the bearer with the S-GWbased on the S-GW Change flag.

Example: In the common location update process, that is, when ISR isactivated in the UE, the new intermediate NE sends a request forobtaining the context information from the original intermediate NEs inthe two systems. The Context acknowledgement message sent by the newintermediate NE to the original intermediate NE in the same systemcontains the S-GW Change flag, indicating that the S-GW is changed. Inthis case, after receiving the Cancel Location request from the originalintermediate NE, the new intermediate NE in the same system decideswhether to initiate a request for deleting the bearer with the P-GW orwith the S-GW or to delete the context information stored in itselfbased on whether the Context acknowledgement message and S-GW Changeflag are received.

Method B: In the Update Location request, the Update Type flag iscarried to indicate whether the Update Location procedure is or issimilar to the Attach procedure (that is, the UE accesses the system forthe first time after the detach procedure) or the Update Locationprocedure is an ordinary location update procedure. If it is an ordinarylocation update procedure, the S-GW Change flag needs to be carried.

The Cancel Location request sent by the HSS to the original entity (forexample, the original MME) carries the same information, that is,Cancellation Type. The value of Cancellation Type equals the Update Typeinformation. In this case, if the Cancellation Type indicates an attachtype (it indicates that the UE accesses the network for the first timeafter the detach procedure), and related bearer exists in the originalentity, a request for deleting the bearer with the S-GW and with theP-GW is initiated. For example, the original MME initiates a DeleteBearer request to the S-GW and the P-GW to delete the bearers that areleft due to last abnormal power-off of the UE.

If the carried Cancellation Type is Update or RAU/TAU (it means that theUE accesses the network before), the S-GW Change flag is checked. If theS-GW Change flag is carried, that is, the S-GW is changed, the originalentity initiates a request for deleting the bearer with the S-GW;otherwise, the original entity deletes the UE context information storedin the original entity.

In this example, if the original MME detects that the Cancellation Typein the Cancel Location message from the HSS is TAU, and the S-GW Changeflag is carried, the original MME sends a Delete Bearer Request messagewith the S-GW Change flag to the S-GW. The S-GW receives the message andfinds that the S-GW Change flag is contained. The S-GW does not send arequest for deleting the bearer to the P-GW. If the original MME findsthat the Cancellation Type in the Cancel Location message is TAU, andthe S-GW Change flag is not carried, the original MME deletes the UEcontext information stored in the original MME but does not send arequest to the S-GW for deleting the bearer. If the original MME findsthat the Cancellation Type in the Cancel Location message indicates anattach type, and relevant bearer exists, the original MME sends a DeleteBearer Request message to the original S-GW to request for deleting thebearer with the S-GW. The S-GW does not receive the S-GW Change flag andthus sends a request for deleting the bearer with the P-GW.

Method C: The new entity sends a notification message to the originalentity in the system. In this example, the ordinary TAU procedure isinvolved. Therefore, the new MME sends a Context Acknowledge or othermessage to the original MME before step 410 to inform the original MMEwhether the S-GW is changed. The original MME receives the message andlearns that the ordinary TAU procedure is involved. If the UE accessesthe SAE network for the first time, the new MME does not send such amessage, or the message carries a parameter to indicate whether theordinary TAU procedure or a procedure similar to Attach is involved.This message can carry the parameter that specifies the S-GW Changeinformation. If the S-GW is changed, the original MME sends a requestfor deleting the bearer to the original S-GW but not the bearer with theP-GW. If the S-GW is not changed, the original MME deletes the UEcontext information stored in the original MME. Or, after the SGSNlearns that the MME is changed, the SGSN establishes association withthe new MME, and sends a message to the original MME to cancel theassociation with the original MME. In this case, the original MME learnsthat the UE initiates an ordinary TAU procedure. The Contextacknowledgement message sent by the new MME to the SGSN specifieswhether the S-GW is changed. Based on this information, the SGSN decideswhether to carry the S-GW Change flag in the message sent to theoriginal MME. Thus, the original MME decides whether to send a requestfor deleting the bearer with the S-GW or to delete the UE contextinformation stored in the original MME.

Method D: After receiving a Cancel Location message from the HSS, theMME or SGSN sends a delete bearer request message to the S-GW if the MMEor SGSN does not receive the context request or context acknowledge orreceives an S-GW change flag. The S-GW decides whether to delete thebearer or to send a request for deleting the bearer with the P-GW. Ifthe S-GW learns that ISR is not activated or is to be deactivated (forexample, when the S-GW receives an ISR indication from another entity),or if the S-GW does not receive the S-GW Change flag in the deletebearer request message, the S-GW deletes its own bearer and initiates arequest for deleting the bearer with the P-GW. If the S-GW learns thatISR is activated, and no S-GW Change flag is received, the S-GW returnsa Delete Bearer Response message but does not delete its own bearer orsend a request for deleting the bearer with the P-GW.

For method D, another bearer deletion method is provided herein in anembodiment of the present disclosure as follows: After the UE accessesan RAT network for the first time after the attach procedure, the UEinitiates a location update request. This request contains a specialflag, for example, the indication of the UE accessing the RAT networkfor the first time after the attach procedure. In this case, theaccessed intermediate NE or new intermediate NE learns that the UEaccesses this RAT network for the first time. If the new intermediate NEcontains the UE bearer information, the new intermediate NE initiates arequest for deleting the bearer between the NE and the S-GW and thebearer between the S-GW and the P-GW. If the new intermediate NE doesnot contain the UE bearer information, the intermediate NE initiates anUpdate Location request to the HSS, which contains the attach type flag.

A bearer deletion method is provided herein as follows: The originalintermediate NE receives a Cancel Location request from the HSS andsends a bearer deletion request to the S-GW. If the S-GW learns that ISRis activated, the S-GW sends a bearer deletion response to the originalintermediate NE but does not delete any bearer. If the S-GW learns thatISR is not activated or is to be deactivated, the S-GW sends a requestfor deleting the bearer between the S-GW and the P-GW and the bearerbetween the original intermediate NE and the S-GW.

In other words, if the ordinary location update procedure is involved,no request for deleting the bearer with the P-GW is sent. If theordinary location update procedure is involved and the S-GW is changed,the intermediate NE, such as the SGSN and MME, sends a request fordeleting the bearer with the S-GW but does not send a request fordeleting the bearer between the S-GW and the P-GW. If the S-GW is notchanged, the intermediate NE deletes the UE context information storedin the intermediate NE. If the Attach or Attach-like procedure isinvolved (that is, the location update procedure when the UE accesses asystem for the first time after the detach procedure), the last detachedintermediate NE of the system needs to delete the bearer with the S-GWand the bearer with the P-GW (if any) to avoid any bearer that is leftdue to abnormal power-off of the UE.

In this example, when the MME is changed, different methods can be usedto implement the bearer deletion flow, thus improving the flexibility ofbearer deletion.

The scenario inside the SGSN is described as follows:

Case Four: The UE switches from an MME to an SGSN when ISR is activated.

FIG. 5 shows the fourth case of the bearer deletion method in anembodiment of the present disclosure, including:

Step 501: The UE sends an RAU request.

The UE sends an RAU Request message to the new SGSN.

Step 502: The new SGSN sends a context request to the MME.

Step 503: The MME sends the context information to the new SGSN.

Step 504: The authentication procedure may be performed.

Step 505: The new SGSN sends the Context acknowledgement message orexplicit signaling to the MME.

Step 506: A request for creating PDP context or a request for creating abearer is sent.

The new SGSN sends a request for creating PDP context or a request forcreating a bearer to the S-GW.

Step 507: If the S-GW or related parameters are changed, the S-GW sendsa bearer update request to the P-GW.

The S-GW sends a bearer update request to the P-GW.

Step 508: The P-GW sends a bearer update response.

Step 509: The PDP context setup response is sent.

Step 510: The new SGSN sends an Update Location request to the HSS.

Step 511: The original SGSN and the HSS perform the Cancel Locationprocedure.

Step 512: The PDP context request is deleted.

Step 513: The HSS may insert the data about the UE to the new SGSN.

514: The HSS sends an Update Location response to the new SGSN.

Step 515: The new SGSN sends a message to the UE, indicating that theRAU request is accepted.

Step 516: The UE sends a message to the new SGSN, indicating that theRAU is complete.

The bearer deletion methods are similar to the preceding description.When the S-GW is changed, the Delete PDP Context Request or DeleteBearer Request message needs to carry the S-GW Change flag. Thefollowing table describes the modification of the message if required.

Information element Presence requirement Teardown Ind Conditional NSAPIMandatory Protocol Configuration Options Optional Private ExtensionOptional S-GW Change Conditional

The new parameter is S-GW Change or a parameter that indicates the S-GWchange information, for example, Cause. A certain cause value is used toindicate the S-GW change information. This cause value needs to becarried when the S-GW is changed.

Case Five: The UE switches from an SGSN to another SGSN when ISR isactivated.

FIG. 6 shows the fifth case of the bearer deletion method in anembodiment of the present disclosure, including:

Step 601: The UE sends an RAU request.

The UE sends an RAU Request message to the new SGSN.

Step 602: The new SGSN sends a context request to the original SGSN.

Step 603: The original SGSN sends the context information to the newSGSN.

Step 604: The authentication procedure may be performed.

Step 605: The new SGSN sends the Context acknowledgement message orexplicit signaling to the original SGSN.

Step 606: The new SGSN sends a request for creating the PDP context.

The new SGSN sends a request for creating the PDP context to the S-GW.

Step 607: The S-GW sends a bearer update request.

The S-GW sends a bearer update request to the P-GW.

Step 608: The P-GW sends a bearer update response.

Step 609: The PDP context setup response is sent.

Step 610: The new SGSN sends an Update Location request to the HSS.

Step 611: The original SGSN and the HSS perform the Cancel Locationprocedure.

Step 612: The PDP context or bearer between the original SGSN and theoriginal S-GW is deleted.

Step 613: The UE data is inserted between the new SGSN and the HSS.

Step 614: The HSS sends an Update Location response to the new SGSN.

Step 615: The new SGSN sends a message to the UE, indicating that theRAU request is accepted.

Step 616: The UE sends a message to the new SGSN, indicating that theRAU is complete.

The original SGSN can learn through the Context acknowledgement messagethat the ordinary TAU procedure is involved. However, if the S-GW ischanged, the Context acknowledgement message needs to carry the S-GWChange information because the original SGSN needs to send a Delete PDPContext Request or Delete Bearer Request message to the S-GW to instructthe S-GW to delete the UE context information.

If the S-GW is not changed, the original SGSN only needs to delete theUE context information stored in the original SGSN.

If the S-GW receives a Delete PDP Context Request or Delete BearerRequest message from the SGSN, and the message does not carry the S-GWChange flag, the S-GW regards that the UE initiates an Attach procedure,and then the S-GW sends a Delete Bearer message to the P-GW.

Therefore, the Context acknowledgement message between the existingSGSNs needs to be modified, as shown in the following table.

Information element Presence requirement Cause Mandatory Tunnel EndpointIdentifier Data II Conditional SGSN Address for user traffic ConditionalPrivate Extension Optional S-GW Change Conditional

The S-GW Change flag or a parameter that indicates the S-GW changeinformation, for example, Cause, needs to be included in this message. Acertain cause value is used to indicate the S-GW change information.This cause value needs to be carried when the S-GW is changed.

It can be inferred that the scenario in which the UE switches from anMME to another MME when ISR is activated is the same as this scenario.

Type II. Cancel Location Procedure Triggered in Two Networks

Case Six: FIG. 7 shows the sixth case of the bearer deletion method inan embodiment of the present disclosure, including:

Step 701: The UE sends an attach request.

The UE initiates an attach request to the new MME.

Step 702: The UE identification is performed (including request andresponse messages).

The new MME sends an identification request to the original MME toobtain the IMSI of the UE.

Step 703: The new MME exchanges messages (including request andresponse) with the UE. If the IMSI of the UE is not obtained, the newMME obtains the IMSI from the UE.

Step 704: The authentication procedure may be performed.

The UE performs authentication with the new MME and the HSS.

Steps 705A to 705D. If the entity that the UE last detached is theentity accessed this time, the bearer deletion request and responsemessages are sent to delete the bearer left due to abnormal power-off ofthe UE.

Step 706: The Update Location request is sent.

The new MME sends an Update Location request to the HSS.

Step 707: The original MME and the HSS perform the Cancel Locationprocedure.

Steps 708A to 708B. A bearer deletion request is sent.

Step 709: The SGSN and the HSS perform the Cancel Location procedure.

Steps 710A to 710B. The PDP context or bearer is deleted.

Step 711: The UE data is inserted between the new MME and the HSS.

Step 712: The HSS sends an Update Location response to the new MME.

In this example, after registering with the new MME, the UE sends anUpdate Location request to the HSS. The HSS sends Cancel Locationrequests to the original MME and the original SGSN to delete the UEcontext information. If the MME is not changed but the UE contextinformation is reserved, the MME does not send an Update Locationrequest to the HSS. As a result, the UE context information on the SGSNcannot be deleted. Therefore, if the UE initiates the Attach procedure,the UE can force the MME to initiate an Update Location request to theHSS even if the MME is not changed.

If the HSS finds that the saved MME is the MME that sends the UpdateLocation request, it indicates that the UE does not change the MME andthus does not need to send a Cancel Location request to the MME thatstores the UE context information. However, the UE sends a CancelLocation request to the SGSN that stores the UE context information.After receiving the request, the SGSN deletes the bearer with the P-GW.

To distinguish between Update Location requests of the ordinary RAU andTAU, the Update Location requests needs to carry the attach flag, theRAU/TAU flag, or a flag that indicates whether the value of Update Typeindicates an attach type or Update. The value of Cancellation Type isthe same as that of Update Type. If the S-GW is changed, the S-GW Changeflag may be required.

After the UE is attached to the SAE network, the HSS has sent a CancelLocation request to the original SGSN. Therefore, the next time when theUE accesses the SGSN, the HSS does not send the Cancel Location requestto the original SGSN or perform bearer deletion. Even if the UE does notchange the SGSN, the SGSN initiates an Update Location request to theHSS because no UE context information exists in the SGSN.

The UE sends the Attach Request message for once. The UE sends an RAU orTAU request after accessing another RAT network for the first time afterthe Attach procedure. When the preceding method is used, that is,deleting the UE context information from all the entities registered bythe UE last time during the attach procedure, it is not necessary tojudge whether the UE accesses the RAT network for the first time afterpower-on. After the RAU or TAU request is received, the Attach flagneeds to be marked in the Update Location message. In this case, theoriginal entity deletes the bearer of the UE.

The preceding example describes the scenario when the UE is attached toan SAE network. The principles for the scenario when the UE is attachedto a 2G or 3G network are the same as those for the preceding scenario.When the UE sends an Attach Request message to a certain intermediateNE, the intermediate NE sends an Update Location request (with UpdateType as Attach) to the HSS. The HSS sends a Cancel Location message tothe original intermediate NEs (those in the 2G/3G network and SAEnetwork) to delete the UE context information and bearer left by the UE.In this case, the UE does not need to identify the procedure whenaccessing another system.

A fixture is provided herein. See FIG. 8: The first case of intermediateNE in the present disclosure includes:

a status obtaining unit 801, configured to obtain the network status ofthe UE;

a parameter setting unit 802, configured to: judge whether the UEperforms the attach procedure or accesses the network for the first timebased on the obtained UE network status, and set the update type flag toAttach if the UE performs the attach procedure or accesses the networkfor the first time based on the obtained UE network status, or set theupdate type flag to Update if not; and

a message sending unit 803, configured to send the Update Locationmessage that contains the update type flag to the HSS.

FIG. 9 shows the second case of the intermediate NE in an embodiment ofthe present disclosure, including:

a context receiving unit 901, configured to receive Context Request,Context Acknowledge, Cancel Location or other explicit messages;

a change judging unit 902, configured to judge whether the ContextRequest, Context Acknowledge, Cancel Location or other explicit messagecontains the Attach, Location Update, or S-GW Change flag; and

a deletion execution unit 903, configured to: initiate a request fordeleting the bearer with the S-GW and the bearer between the S-GW andthe P-GW when the Context Request, Context Acknowledge, Cancel Locationor other explicit message contains the Attach flag; initiate a requestfor deleting the bearer with the S-GW if the message contains the Updateflag and the S-GW Change flag; delete the UE context information if theS-GW Change flag is not contained.

FIG. 10 shows the HSS in an embodiment of the present disclosure,including:

a receiving unit 1001, configured to receive Update Location messagessent by the intermediate NE; and

a sending unit 1002, configured to send Cancel Location messages to theintermediate NE.

The cancellation type indication parameter in the Cancel Locationmessage is the update type flag in the Update Location message receivedby the receiving unit. If the Update Location message received by thereceiving unit carries the S-GW Change flag, the Cancel Location messagesent by the sending unit carries the S-GW Change flag.

FIG. 11 shows the S-GW in an embodiment of the present disclosure,including:

a message receiving unit 1101, configured to receive the request fordeleting a bearer or the request for deleting a PDP context from theintermediate NE;

a message judging unit 1102, configured to judge whether the bearerdeletion request or PDP context deletion request contains a request fordeleting the bearer with the P-GW (if the S-GW Change flag is carried,it indicates that the bearer with the P-GW does not need to be deleted;otherwise, the bearer with the P-GW needs to be deleted); and

a bearer deletion unit 1103, configured to: initiate a request fordeleting the bearer with the P-GW if the said bearer deletion request orthe request for deleting a packet data protocol context contains theindication for deleting the information about the bearer with the P-GWand the relevant bearer exists; otherwise, delete the contextinformation about the UE.

An intermediate NE is provided in an embodiment of the presentdisclosure. The intermediate NE includes:

a receiving unit, configured to receive the Cancel Location message thatcontains the cancellation type indication parameter sent by the HSS; and

a deletion unit, configured to delete the bearer with the S-GW and thebearer between the S-GW and the P-GW when the cancellation typeindication parameter indicates an attach type and relevant bearerexists.

The intermediate NE can be integrated into an MME or an SGSN.

An intermediate NE is provided in an embodiment of the presentdisclosure. The intermediate NE includes:

a receiving unit, configured to receive the Cancel Location message thatcontains the cancellation type indication parameter sent by the HSS; and

a deletion unit, configured to delete the bearer between theintermediate NE and the S-GW when the cancellation type indicationparameter is Update and the S-GW Change flag is received.

The deletion unit is also configured to delete the UE contextinformation stored in the intermediate NE if the cancellation typeindication parameter is Update and the S-GW Change flag is not receivedor an S-GW Not Changed flag is received.

The intermediate NE can be integrated into an MME or an SGSN.

A bearer control system is provided in an embodiment of the presentdisclosure. The bearer control system includes:

a new intermediate NE, configured to indicate the update type flag inthe Update Location message that is sent to the HSS as Attach when theUE accesses the network for the first time;

an HSS, configured to send the Cancel Location message that contains thecancellation type indication parameter to the original intermediate NEwhen receiving the Update Location message from the new intermediate NE,in which the cancellation type indication parameter indicates an attachtype; and

an original intermediate NE, configured to: receive the Cancel Locationmessage that contains the cancellation type indication parameter sentfrom the HSS, and delete the bearer between the original intermediate NEand the S-GW and the bearer between the S-GW and the P-GW when thecancellation type indication parameter indicates an attach type andrelevant bearers exist.

Alternatively, the bearer control system includes:

a new intermediate NE, configured to indicate the update type flag inthe Update Location message that is sent to the HSS as Update when theUE accesses the network for the first time;

an HSS, configured to send the Cancel Location message that contains thecancellation type indication parameter to the original intermediate NEwhen receiving the Update Location message from the new intermediate NE,in which the cancellation type indication parameter is Update; and

an original intermediate NE, configured to: receive the Cancel Locationmessage that contains the cancellation type indication parameter fromthe HSS, and delete the bearer between the original intermediate NE andthe original S-GW if the S-GW Change flag is received or delete the UEcontext information stored in the original intermediate NE if the S-GWChange flag is not received or an S-GW Not Changed flag is received whenthe original intermediate NE determines that the cancellation typeindication parameter is Update.

An intermediate NE is provided in an embodiment of the presentdisclosure, including:

a receiving unit, configured to receive Context acknowledgement messageor explicit signaling sent by the new intermediate NE; and

a deletion unit, configured to delete the bearer between theintermediate NE and the S-GW when the preceding message or explicitsignaling contains the S-GW Change flag and the bearer exists.

The deletion unit is also configured to delete the UE contextinformation stored in the intermediate NE.

Before receiving the Context acknowledgement message or explicitsignaling from the new intermediate NE, the receiving unit is configuredto receive the Context Request message sent by the new intermediate NE.

The intermediate NE further includes a sending unit that is configuredto send the context response to the new intermediate NE.

The deletion unit is also configured to delete the PDP context or bearerinformation stored locally.

An HSS is provided in an embodiment of the present disclosure,including:

a receiving unit, configured to receive the Update Location request sentby the new intermediate NE after the UE initiates an attach request; and

a sending unit, configured to: send the Cancel Location requests to theoriginal intermediate NE and the original intermediate NE in the othersystem registered by the UE, and instruct the two original intermediateNEs to delete the bearer with the S-GW and the bearer between the S-GWand the P-GW when the intermediate NE originally registered by the UE ischanged.

An intermediate NE is provided in an embodiment of the presentdisclosure, including:

an acquisition unit, configured to obtain the context information fromthe original intermediate NE in the own system and the originalintermediate NE in the system registered by the UE; and

a feedback unit, configured to send the acknowledgement message thatcontains the cancellation type indication parameter to the two originalintermediate NEs.

Another intermediate NE is provided in an embodiment of the presentdisclosure, including:

a sending unit, configured to send the UE context information to the newintermediate NE;

a receiving unit, configured to receive the acknowledgement message thatcontains the cancellation type indication parameter sent by the newintermediate NE;

a first deletion unit, configured to delete the bearer between theoriginal intermediate NE and the P-GW when the cancellation typeindication parameter indicates an attach type; and

a second deletion unit, configured to: delete the bearer between theoriginal intermediate NE and the original S-GW when the cancellationtype indication parameter is Update and the S-GW Change flag isreceived, or delete the UE context information stored in the localintermediate NE when the S-GW Change flag is not received.

An S-GW is provided in an embodiment of the present disclosure. The S-GWincludes:

a message receiving unit, configured to receive the request for deletinga bearer or the request for deleting a packet data protocol context fromthe original intermediate NE;

a message judging unit, configured to: determine whether to restrict ISRactivation, and send a bearer deletion response to the originalintermediate NE without deleting the bearer if the ISR is activated andthe S-GW is not changed; or send a request for deleting the bearer withthe P-G and delete the bearer when the ISR is deactivated and the S-GWis not changed.

An intermediate NE is provided in an embodiment of the presentdisclosure. The intermediate NE includes:

a location update receiving unit, configured to receive the UpdateLocation request that contains the flag of the first access to the RATnetwork after attach from the UE;

a deletion unit, configured to initiate the procedure for deleting thebearer between the intermediate NE and the S-GW and the bearer betweenthe S-GW and the P-GW when the bearer information about the UE exists inthe intermediate NE; and

a location update initiating unit, configured to initiate an UpdateLocation request that contains the attach type flag to the HSS when nobearer information about the UE exists in the intermediate NE.

From the preceding technical scheme, the present disclosure has thefollowing advantages:

The intermediate NE receives the cancel location message that containsthe cancellation type indication parameter sent by the HSS, determineswhether the procedure is an update procedure or an attach procedurebased on the cancellation type indication parameter, and decides how todelete bearers. For example, if the cancellation type indicationparameter indicates an attach type, and bearers exist, the intermediateNE deletes the bearer between the intermediate NE and the S-GW and thebearer between the S-GW and the P-GW. Or, the S-GW judges whether todelete its own bearer and the bearer with the P-GW. The preceding methodhelps distinguish between the following procedures: the procedure fordeleting abnormal bearers when the UE accesses the RAT network for thefirst time after the attach procedure; the procedure for deleting orreserving bearers in other scenarios.

A UE is provided in an embodiment of the present disclosure, including asending unit, configured to send an Update Location request when the UEaccesses an RAT network for the first time after the attach procedure.The Update Location request carries the attach flag, indicating that theUE accesses the RAT network for the first time after the attachprocedure.

For the functions and implementation processes of the units of thepreceding equipment, see the implementation flow of the related method.

In the present disclosure, the attach flag, update flag, and S-GW Changeflag are used to indicate whether a UE accesses a certain network forthe first time after the attach or detach procedure, the UE accessed acertain network before, and the S-GW of the UE is changed. Other methodscan be used to indicate this information. For example, certain causevalues can be adapted. The present disclosure provides an option butdoes not confine the method for illustrating such difference.

Those skilled in the art can complete all or part of the steps in thepreceding method by using a program to instruct related hardware. Theprogram can be stored in a storage medium that can be read by acomputer. The procedure for executing the program is as follows: Theoriginal intermediate NE receives the cancellation type indicationparameter sent by the HSS. If the cancellation type indication parameterindicates an attach type, and the original intermediate NE containsrelevant bearers, the original intermediate NE deletes the bearerbetween the original intermediate NE and the S-GW and the bearer betweenthe S-GW and the P-GW.

The preceding storage medium can be a read-only storage, a disk, acompact disk (CD), or other suitable storage medium (magnetic (volatileand non-volatile), optical, etc.).

Detailed above are a bearer deletion method, an intermediate NE, anS-GW, an HSS, and a bearer control system in an embodiment of thepresent disclosure. It is apparent that those skilled in the art canmake various modifications and variations to the disclosure withoutdeparting from the spirit and scope of the disclosure. The disclosure isintended to cover the modifications and variations provided that theyfall in the scope of protection defined by the following claims or theirequivalents.

What is claimed is:
 1. A method for managing bearer resources when aterminal device changes its attachment from a first intermediate networkelement to a second intermediate network element, comprising: sending,by the second intermediate network element to a home subscriber server(HSS), an update location message, wherein the update location messagecarries an update type flag, the update type flag indicates whether theterminal device is performing an attach procedure or a location updateprocedure; sending, by the HSS to the first intermediate networkelement, a cancel location message, wherein the cancel location messagecontains an indicator indicating a cancellation type; when thecancellation type is an attach type, and a bearer corresponding to theterminal device exists on the first intermediate network element,sending, by the first intermediate network element to a serving gateway,a first request for deleting the bearer, and sending, by the servinggateway to a packet data network gateway, a second request for deletingthe bearer after receiving the first request; or when the cancellationtype is an update type, a bearer corresponding to the terminal deviceexists on the first intermediate network element, and a serving gatewaychange indication is received by the first intermediate network element,sending, by the first intermediate network element to the servinggateway, a third request for deleting the bearer; or when thecancellation type is the update type, and the serving gateway changeindication is not received by the first intermediate network element,deleting, by the first intermediate network element, context informationcorresponding to the terminal device stored in the first intermediatenetwork element.
 2. The method according to claim 1, wherein the firstintermediate network element is a mobility management entity or aserving general packet radio service support node.
 3. The methodaccording to claim 1, wherein the second intermediate network element isa mobility management entity or a serving general packet radio servicesupport node.
 4. A network system, comprising a first intermediatenetwork device, a second intermediate network device, a home subscriberserver (HSS) and a serving gateway, wherein when a terminal devicechanges its attachment from the first intermediate network device to thesecond intermediate network device, the second intermediate networkdevice is configured to send an update location message to the HSS,wherein the update location message carries an update type flag, and theupdate type flag indicates whether the terminal device is performing anattach procedure or a location update procedure; the HSS is configuredto send a cancel location message to the first intermediate networkdevice, wherein the cancel location message contains an indicatorindicating a cancellation type; and the first intermediate networkdevice is configured to: when the cancellation type is an attach type,and a bearer corresponding to the terminal device exists on the firstintermediate network device, send a first request to the serving gatewayfor deleting the bearer, wherein the serving gateway sends a secondrequest for deleting the bearer to a packet data network gateway afterreceiving the first request; or when the cancellation type is an updatetype, a bearer corresponding to the terminal device exists on the firstintermediate network device, and when a serving gateway changeindication is received by the first intermediate network device, send athird request for deleting the bearer to the serving gateway; or whenthe cancellation type is the update type, and the serving gateway changeindication is not received by the first intermediate network device,delete context information corresponding to the terminal device storedin the first intermediate network device.
 5. The network systemaccording to claim 4, wherein the first intermediate network device is amobility management entity or a serving general packet radio servicesupport node.
 6. The network system according to claim 4, wherein thesecond intermediate network device is a mobility management entity or aserving general packet radio service support node.